Motor fuel



Patented June 8, 1943 MOTOR FUEL August Y. Mottlau,

Clark Township,

Union County, and Pharis Miller, Elizabeth, N. J., assignors to Standard Oil Development Company, a-corporation of Delaware No Drawing. Application October 21, 19?;9,

Serial No. 300,554

10 Claims.

This invention relates to motor fuels and, particularly to blending ingredients which impart increased anti-knock value to fuels used in operating high-compression spark-ignition engines.

With the demand for motor fuels of higher octane number increasing, a number of new fuel blending agents such as branched ethers, branched ketones, and alcohols have been developed. Notwithstanding these developments, there is further need for additional sources of fuel ingredients, particularly ingredients having octane ratings of the order of 100 or higher, good susceptibility to anti-knock agents such as tetraethyl lead and with volatility characteristics which distribute high anti-knock value increases more uniformly throughout the boiling range of a fuel. It is an object of this invention to provide such desired motor fuel ingredients.

In accordance with the present invention, heterocyclic organic compounds of the furane group, particularly furane, itself, alkyl-substituted furanes and their saturated analogues are readily obtainable compounds which have satisfactory high anti-knock ratings and suitable volatilities for supplementing other components of a fuel.

Furane, otherwise known as furfurane, is a colorless mobile liquid. It is obtained in a distillation of sugar with lime; it is present in wood tar distillates; it can beformed simply from pentoses, pentosans, furfural, and such substances which are easily obtained from corn cobs, oat hulls, and similar cheap agricultural by-products. Furane is represented by the constitutional formula:

Closely allied to furane in origin and charteristics are the alkyl-substituted furanes, e. g.

alpha methyl furane which boils at 149 F., and dimethyl furane which boils at about 200 F.

The alkyl derivative homologues of furane are represented by the generalized formula:

RCCR

II II BC on carbons or motor fuel bases in volumetric proportions of 1%, 5%, 0%, and higher.

As one particular example, about 1 /2% of furane in a blend with a. standardized gasoline reference fuel raised the clear octane number of the fuel from 78.5 to 80.4 as determined by the Army method. This indicates that furane has a blending value of about 200. With 3 cc. of tetraethyl lead present per gallon of the blend, the octane value is raised from 94.5 to 96.1 with about 1 /2% of furane blended with the fuel. giving the furane in this instance also a blending value of about 200.

As a further example, 2,5 dimethyl furane blended with the standardized reference fuel in a 1% concentration by volume raised the A. S. T. M. octane number of the hydrocarbon fuel from 78.7 to 79.5, showing that this alkyl-substituted furane has a blending value of 160. With 3 cc. of tetraethyl lead added per gallon of fuel, the increase of octane rating effected by the same concentration of the alkyl furane was from 94.5 to 94.7, showing that the alkyl furane had a satisfactorily high lead susceptibility with a blending value of 110.

By addition of a 5% by volume concentrationof the 2,5 dimethyl furane in the standardized gasoline reference fuel containing 3 cc. of tetra- 'ethyl lead per gallon, the Army octane number of the fuel was found to be raised from 94.5 to a 95.5 which indicates that even in higher concentrations the alkyl furane still shows a high blending value of 114 and good lead susceptibility,

By virtue of its high anti-knock value with a high volatility, furane is advantag'eousfor raising front end volatility when used with other high octane fuel ingredients such as iso-octane, which has an octane rating of about to and boils at about 248 F. However, to increase the octane rating beneficially of a safety fuel or of higher ends of gasoline, the higher boiling alkyl furane homologues may be advantageously used, It is thus possible to distribute the increase in antiwater, the same as hydrocarbons, and are distinct in this manner from compounds such as furfural and alcohols. While alcohols are known to have good blending value, they have the disadvantage of being dropped out by slight additions of water. The furanes are water-white, and, therefore, maintain good color in a gasoline solution. It might be noted that furane and its derivatives form dyes with certain compounds, such as isatin and phenanthrene quinone, and accordingly, it may be used as an identifying agent in the fuel.

In general, the furanes are non-toxic and have an inoffensive odor in a fuel. They are relatively stable to oxidation compared to aliphatic ethers. When it is desired to assure their stability in high grade fuels, small amounts of well-known stabilizing compounds such as aromatic amines and phenols may be added to the fuel, or the furane may by hydrogenated to saturate the double bonds. The hydrogenation to form tetrahydrofuranes is readily accomplished by known methods, as for example, by passing the furanes at about 100 C. to 200 C. together with hydrogen over a hydrogenation catalyst, such as nickel.

Although furane and its alkyl derivatives, both saturated and unsaturated, are preferred as blending agents on account of their many advantageous qualities, at times it may be desirable to supplement or replace these compounds by furane derivatives which contain an amino group or a hydroxyl group, e. g. furfuryl amines, tetrahydrofurfuryl amines, furfuryl alcohols, and tetrahydrofurfuryl alcohols. Although the unsaturated amines and alcohol derivatives of furane are relatively less soluble per se in hydrocarbon oils, they partake of beneficial properties belonging to the furane nucleus, having satisfactory anti-knock blendingc-values, and being solubilized by furane and its alkyl derivatives. The saturated furfuryl alcohols and amines, however, have both good oil solubilities and high anti-knock blending values even though they are excelled, in general, in these respects by furane and its alkyl and hydrogenated derivatives. By way of example, tetrahydrofurfuryl alcohol, C4H1O-CHzOH,

be any liquid hydrocarbon oil adapted for use in spark-ignition engines of the carbureter or injection type. For the carbureter type engine, the fuel should boil within the range of 100 F. to 450 F.; for the injection type, the end point of the fuel may be as high as 500 F., or even 600 F. The base fuel may be a gasoline obtained by the known commercial methods of refining.

It may include pressure distillate naphtha hydrocarbons prepared by thermal or catalytic cracking processes, naphtha hydrocarbons formed by polymerization of olefins, or their hydrogenated derivatives. When prepared as a high flash point safety fuel, the naphtha hydrocarbons should boil preferably in the range of 200 F. to 600 F. The furane blending agents boiling within the boiling range of the desired fuel are preferably selected for addition to the fuel base.

By virtue of their high miscibility with hydro carbon motor fuels, the furanes, including both alkylated and hydrogenated derivatives, may be employed in motor fuel compositions together with other additive improving agents, such as anti-oxidants, gum solvents, corrosion inhibitors, metallic anti-knock agents, and other antiknock blending agents. As illustrated by the examples, the furanes are remarkably effective together with lead alkyl anti-knock agents.

It is not intended that the invention be limited to any of the specific examples. It is to be understood that any modification coming within the scope of this invention is desired to be claimed together with all novelty inherent in the invention.

We claim:

1. A motor fuel composition comprising a mixture of gasoline hydrocarbons adapted as a base .fuel for spark-ignition engines improved in antiwhich a mixture of said heterocyclic compounds is added in an amount of at least 1% by volume of the composition.

3. A composition as described in claim 10, containing in addition a small amount of a lead alkyl anti-knock agent.

4. A motor fuel comprising gasoline hydrocarbons improved in octane number by the addition of at least 1% by volume of furane.

5. A motor fuel comprising gasoline hydrocarbons improved in octanenumber by the addition of at least 1% by volume of furane and a small amount of a lead alkyl anti-knock agent.

6. A motor fuel comprising safety fuel naphtha hydrocarbons and at least 1% by volume of furane containing alkyl substituents, said alkyl substituted furane boiling in the boiling range of the fuel hydrocarbons.

'7. A motor fuel comprising gasoline hydrocarbons and at least 1% by volume of a hydrogenated furane boiling in the gasoline boiling range.

8. A motor fuel comprising a mixture of hydrocarbons of the gasoline boiling range improved by an addition of a mixture of monocyclic furanes in suflicient amount of at least 1% by volume to distribute increases in octane value to portions of the fuel having varying volatilities, said furanes consisting of hydrogen, carbon, and oxygen, and containing only one oxygen atom per molecule. said oxygen atom being in the furane nucleus, and said furanes boiling in the boiling range of gasoline. A

9. A motor fuel comprising gasoline hydrocarbons improved by an addition of 1% to 50% by volume of 2,5 dimethyl furane.

10. A motor fuel composition consisting essentially of a gasoline base fuel boiling in'the range of F. to 450 F,, improved in octane number by an addition of from 1% to 10% of a monocyclic furane compound consisting of hydrogen. carbon and oxygen, and containing only one oxygen atom per molecule, said oxygen atom being in the furane nucleus, and said furane compound boiling below the end point of the base fuel,

AUGUST Y. MOTTLAU. PHARIS MILLER. 

